1. Field of the Invention
The present invention generally relates to a magnetic coil structure, and more specifically to a magnetic excitation coil structure having a thin magnetic coil sheet rolled to form a multiple layered cylindrical body and covered by an insulation layer.
2. The Prior Arts
In general, an electric coil can be manufactured by simply winding a traditional enameled wire to form a ring shape, and is a common electric element used as a normal inductor or providing induced magnetic field for electromagnetic force. In particular, it needs specific magnetic excitation material to increase efficiency of conversion from magnetic flux into magnetic field. It is well known that the electrical property of the coil is improved as the winding density of the enameled wire increases. How to effectively increase the winding density is thus always one of the crucial topics for the manufacturers.
Recently, the rigid board technology has been used to manufacture the coils with the high winding density. In the rigid board technology, the electric circuit pattern is formed as the conductive wire to replace commonly used enameled wire. The aspect ratio of the electric circuit pattern is usually 2:1 or 1:1 only, and it is difficult to increase the aspect ratio up to 1:2 or more. As a result, magnetic flux and electromagnetic effect can not be further improved due to limited winding density, and overall performance and the application field are adversely affected.
Therefore, it is greatly needed to provide a new magnetic excitation coil structure directly employing current manufacturing equipments to increase the aspect ratio up to 1:2 or more, improve electrical performance of coil and enhance magnetic flux and electromagnetic effect, thereby overcoming the above problems in the prior arts.